******The mature dry soybeans are seldom used as cooked vegetable even in the traditional soybean consuming areas. Why is that?
First, because of their high protein content and low starch content, soybeans require much longer cooking than most other beans, generally 5-6 hours without pressure (but only 25-30 minutes at 15 pounds pressure), and even after this they never get as soft as most beans. Also, this long cooking uses lots of fuel, which has always been relatively expensive in densely populated areas. Moreover, the water in China is generally hard (rich in calcium), which further increases the required cooking time. Second, boiled or baked whole soybeans are more difficult to digest than most other soyfoods and than some other dry beans; the oligosaccharides they contain, which are removed in the processing of most soyfoods, can cause flatulence. And third, most East Asian people prefer the flavor and versatility of other soyfoods. (People in countries that have not traditionally consumed soybeans often describe them as having a "beany" flavor). Yet throughout East Asia, whole dry soybeans have long been used in certain dishes at certain times.